Organic electrolyte cells utilizing solid depolarizers have gained considerable interest for applications usually filled by aqueous alkaline cell systems. However, one drawback in the use of organic electrolyte cell systems is that they have relatively low conductivities compared to conventional aqueous cell systems of equivalent size and construction.
To increase the interfacial area contact between active cell components and thereby decrease the resistance of the cell, coiled electrode assemblies have been employed. This type of cell construction employs rolled or coiled electrode assemblies (jelly roll construction) which are widely known in the battery art and are usually placed in a composite housing which serves as the current conductive terminals for the cells. In such structures, the electrode of one polarity is generally electrically connected to a conductive housing portion, and the electrode of the opposite polarity is generally electrically connected to another conductive housing portion which is insulated relative to the electrically conductive first-mentioned housing portion. The electrical contact between each electrode and its respective housing portion is generally formed by an elongated flexible electrically conductive connecting tab or element which is secured at one end to the electrode and at the other end is secured to the respective housing portion.
Although the coiled electrode assembly has found acceptance in such cell systems as nickel/cadmium and systems employing liquid active cathode depolarizers, the advantage of increased interfacial area of the positive and negative electrode which provides for increased conductivity is offset by the disadvantage of the physical imbalance in the electrochemically utilizable active materials due to the coil construction. Specifically, the coiled electrode assembly uses electrode strips or sheets of uniform thickness throughout its entire length which results in sections of the outermost and/or innermost wound electrodes having an opposing electrode only on one side. Thus this results in a physical imbalance in the electrochemically utilizable active materials thereby wasting space that could be occupied by additional utilizable active material that could contribute to the output capacity of the cell.
It is an object of the present invention to provide a coiled electrode assembly for various cell systems that will allow for a substantial physical balance of the electrochemically utilizable active materials thereby resulting in increased output capacity for a given cell size.
Another object of the present invention is to provide a coiled electrode assembly in which the segment of the electrode strip that is not sandwiched between layers of the other electrode strip will have an average thickness less than the average thickness of the remaining portion of the electrode strip that is sandwiched between layers of the other electrode strip.
Another object of the present invention is to provide an organic electrolyte cell employing a solid cathodic electrode strip and an anodic electrode strip that are longitudinally offset and then helically wound into a coiled electrode assembly that will provide excellent output capacity for a given cell size.
Another object of the present invention is to provide a cylindrical MnO.sub.2 or CF.sub.x /organic electrolyte/lithium cell having a relatively good conductivity and output capacity for a given cell size.
The foregoing and additional objects will become more fully apparent from the description hereinafter and the accompanying drawings.